This invention relates to a closure member for a reclosable thermoplastic bag wherein the closure member creates a clicking noise when the closure member is being opened or closed and to a reclosable thermoplastic bag having the closure member. Further, the closure member imparts a vibration or bumpy feel which is tactile and readily perceptible to the touch when the closure member is closed.
In particular, the present invention is concerned with reclosable zippers and thermoplastic zippered bags of the type described in commonly-assigned U.S. Pat. No. 5,070,584 (the '584 patent), such patent being hereby incorporated herein by reference.
The '584 patent discloses a zipper for a reclosable thermoplastic bag having opposing rib and groove profiles wherein at least one of the opposing zipper profiles has a longitudinally extending part interlockable and substantially free of interdigitation with the opposing profile and wherein the part is structurally discontinuous along its length. When the rib and groove profiles are interlocked, an audible clicking sound and/or a vibratory or bumpy feel perceptible to the touch is imparted.
The bags described in the '584 patent provide confirmation of their closure by producing a distinctive tactile and/or audible indication of the interlocking of the male and female profiles in their zippers. This tactile and/or audible indication of the proper interlocking of the male and female profiles is produced by varying the closure force required to interlock the male and female profiles over the length of the zipper. Typically the closure force is cycled intermittently over the length of the zipper between a low closure force and a high closure force, with the changes in closure force being produced in turn by making one or both of the profiles intermittently structurally discontinuous. These intermittent structural discontinuities are manifest in the form of first and second differently-shaped segments over the length of a profile part interlockable with the opposing profile. The differently-shaped segments interlock differently with corresponding portions of the opposing profile and implicate different closure forces.
The magnitude of force required to interlock the male and female profiles of a zippered bag is important to consumers since the forces required to close or zip a zipper in reclosable thermoplastic zippered bags must be low enough to be easy to close the bag and provide the user of the bags a degree of certainty or assurance of closure given by the zippers in such bags and yet the closing force should not be so high that it would be difficult to close or zip the bag.
The zipper profiles disclosed in the '584 patent have worked tremendously well in thermoplastic bags of the prior art and have adequately addressed the problem pertaining to the determination of closure or nonclosure of the zipper of a reclosable bag which such determination is often difficult save with a close visual examination. Prior to the invention of the '584 patent, closure members on reclosable bags did not impart a vibratory or bumpy feel or impart audible clicking sounds along its length between the ends of the closure member as it is being closed or interlocked.
There still exists a need for alternative and improved thermoplastic closure members that impart a vibration perceptible to the touch, and emanate an audible clicking sound along the closure member's length when being closed or interlocked so that the fact of closure can be confirmed by a nonvisual means, i.e., by sound and feel.
Accordingly, it is desired to provide a reclosable bag having an improved closure member that imparts a vibration perceptible to the touch, and, further preferably, emanates an audible clicking sound continually along the closure member from end to end; and it is desired to provide a reclosable bag having a closure member having a low average closing force while still maintaining the bag's integrity, i.e., the high burst strength of the bag.